1. Field of the Invention
The present invention relates to a three-dimensional knitted fabric having unevenness and, more specifically, to a three-dimensional uneven knitted fabric which is free from stickiness and uncomfortableness which may otherwise occur due to sweat.
2. Description of Related Art
Three-dimensional knitted fabrics comprising front and back ground structures and an interconnection yarn uniting the front and back structures are used in various fields because of their excellent repulsive, cushioning and air permeability.
In the field of garments, the three-dimensional knitted fabrics are used for ordinary garments, sportswear and innerwear. In the field of upholstery materials, the three-dimensional knitted fabrics are widely used as cushioning materials for automobile seats, chairs and beds. By providing an uneven pattern on a surface of such a three-dimensional knitted fabric, the total area of surface portions of the fabric to be brought into contact with human body is reduced, thereby improving the air permeability and texture of the fabric.
Several methods are proposed for providing an uneven pattern on a surface of a woven or knitted fabric. For example, Japanese Examined Patent Publication (KOKOKU) No. 1-40135 (1989) proposes that a ribbed stripe pattern is formed on a woven or knitted fabric by applying high-pressure liquid streams onto the fabric.
Japanese Unexamined Patent Publication (KOKAI) No. 4-146246 (1992) proposes that a pattern is formed on a knitted fabric by heat-pressing the knitted fabric by means of a calender roll.
Further, a method for forming a three-dimensional pattern on a fabric produced with the use of a heat-shrinkable yarn through heat-treatment is proposed (Japanese Unexamined Patent Publications (KOKAI) No. 4-222260 (1992) and No. 4-327259 (1992)).
However, the ribbed pattern formation method employing the high pressure liquid streams is disadvantageous with difficulty in sustaining the ribbed pattern for a long period of time. The method employing the heat press is disadvantageous in that the resulting fabric is poor in texture with its stitches collapsed and with its surface hardened. The method employing the heat-shrinkable yarn is disadvantageous in that the resulting fabric is less uneven with a smaller level difference.
There are known methods for forming an uneven pattern in a knitted structure without any of the aforesaid post treatments. For example, Japanese Unexamined Patent Publication (KOKAI) No. 9-137380 (1997) discloses a method for forming an uneven structure by mesh stitches, broad stitches and tuck stitches. Further, in Japanese Unexamined Patent Publication (KOKAI) No. 2001-11757, the inventors of the present invention disclose a method for forming an uneven pattern on a fabric by knitting two types of yarns having different finenesses while adjusting a traverse width.
These methods indeed provide the uneven pattern on the fabric. However, the uneven pattern is not satisfactory with a smaller level difference and with a greater total area of projections to be brought into contact with human body. Particularly where such a fabric is employed for an automobile seat, stickiness and sweatiness cannot satisfactorily be eliminated which may occur, for example, when a person sits on the seat for a long period of time in summer.